This box has the entrance hole in the underside of the box. Supposedly, this location befuddles the sparrows, but the Bluebirds have no prob figuring it out. Does anyone have experience with this type box and know if it works or not? Article and pix here: http://issuu.com/shoppernews/docs/halls_fc_shopper-news_041513 John Skaggs Powell, Knox Co., TN